After spending eight years translating the first third of James Joyce's famously opaque novel Finnegans Wake into Chinese, Dai Congrong assumed it was a labour of love rather than money. The book's language is thick with multilingual puns and brazenly defies grammatical conventions. It begins: "riverrun, past Eve and Adam's, from swerve of shore to bend of bay, brings us by a commodius vicus of recirculation back to Howth Castle and Environs."

So the 41-year-old professor at Shanghai's Fudan University was incredulous when the translation became a surprise bestseller in China after hitting shelves last month. Backed by an elaborate billboard ad campaign, the first volume of "Fennigen de Shouling Ye" sold out its first run of 8,000 copies and reached number two on a prestigious bestseller list in Shanghai, second only to a biography of Deng Xiaoping. Sales of 30,000 are considered "cause for celebration" according to Chinese publisher Gray Tan, so 8,000 in a month has made Joyce a distinctly hot property. Ian McEwan, for instance, is considered pretty buzzy in translation, but the print run of Atonement was only 5,000 copies.

"At first I felt very surprised, and I feel very surprised now still," says Dai. "I thought my readers would be scholars and writers, and it wouldn't be so popular."

She traces her love of Ulysses back to her time as a doctoral student at Nanjing University in the late 90s – the novel was first translated into Chinese in 1995. With some prodding from her academic adviser, she decided to tackle Finnegans Wake in 2004 and signed a translation contract with a publishing agency two years later.

Joyce is a recent arrival to China. His work was shunned as bourgeois western literature under Mao Zedong – A Portrait of the Artist as a Young Man wasn't translated into Chinese until 1975, a year before Mao's death. And not for lack of demand. When a Chinese version of Ulysses hit shelves just under 20 years later, it promptly sold 85,000 copies.

Dai ventures that Chinese readers may appreciate Joyce's rumination on the cyclical nature of history, the relationships between his male and female characters, and the sheer challenge of interpreting his prose. She describes translating Joyce's famous stream-of-consciousness writing style as an enormous challenge.

"The things I lost are mostly the sentences, because Joyce's sentences are so different from common sentences," she says, adding that she often broke them up into shorter, simpler phrases – otherwise, the average reader "would think that I just mistranslated Joyce. So my translation is more clear than the original book."

Yet she took great pains to remain as faithful to the original as possible. "For example, there was a phrase in Finnegans Wake that said 'sputtering hand', which might mean shaky. If I translated it as 'shaky hand', that would be OK – in Chinese it's a good sentence. However, I just translated it as 'sputtering hand'. Sputtering and hand cannot be put together in Chinese grammar, but I put the two together anyway."

Dai was originally cowed by the scale of the undertaking – the French translation took 30 years to complete – and occasionally considered quitting. "It is a kind of torture," she said. "In China, translation is not regarded as an academic achievement – I have to publish first, and then give my own time to translation."

She often quarrelled with her husband (he wanted her to go to bed; she wanted to stay awake and translate), and was driven to distraction trying to balance the project with family. "My body suffered from the work, working every night," she said. "I looked older than I should be. My eyes became dark, and my skin wasn't that good either."

Her contract covers the remaining two-thirds of the novel, and despite the long hours, she has no qualms about continuing. "I think it's a very great book – after I read Finnegans Wake… I'll think oh, this writer used a sentence that's too traditional, too simple, and if he can experiment more with his sentences then he might be able to express different things."

"Finnegans Wake made me believe that Joyce is a writer who is never satisfied with what he's already accomplished," she continues. "His spirit is very strong."

That is one thing they have in common.

Sign up for the Guardian Today

Our editors' picks for the day's top news and commentary delivered to your inbox each morning.